1999 4.0 OHV loses power

[Pigdog63]

Hey all.
I have a 1999 Explorer XLT with a 4.0 OHV. The codes and the local Ford dealer tell me i need a new Left O2 sensor.
Here is my problem.
Driving along, the engine will lose power. It barely accelerates and will eventually stall. I'll start it up again and it will run fine for a bit, then do the same thing. If i put it in neutral before it stalls, it will sometimes start running ok again, but not always.
So far, i have:
Replaced the entire exhaust system from the manifold gaskets back.
Replaced the fuel filter.
Replaced the ignition coil and wires.
Replaced the old plugs with irridium ones.
The old plug #4 was fouled and it was brand new. Less than 50 miles.
Replaced the intake manifold gasket.
I also put Barrs stop leak in thinking it might be a head gasket leak.
Could a bad O2 sensor cause this?
Fuel pump?
I've already dropped $2000 inro it, almost as much as i paid for it.
Any ideas?

 

[96eb96]

# 4 is drivers side (left). Coolant does ruin o2 sensors. Are you losing coolant? Also , a dirty MAF can cause symptoms like that, but usually you would get codes for both sides. Clean it and see. Fuel pressure can certainly be checked.

What are fuel trims at idle and 1500 RPM (LTFT and STFT).

Hey all.
Driving along, the engine will lose power. It barely accelerates and will eventually stall. I'll start it up again and it will run fine for a bit, then do the same thing. If i put it in neutral before it stalls, it will sometimes start running ok again, but not always.

Another thing could a be a torque converter that don't unlock.

 

[Pigdog63]

Turns out that it was the O2 sensor after all. Replaced it with one from Rock Auto and it's been running smooth.
Thanks all.